Pride ego and boredom
that pretty much sums about him LOL
He is propably resenting Heesoo for how his life turned out because of her.
He was a great student, could have gone to college, probably landing a high-paying job, having an easy life.
I bet he felt stuck, fed up with his life with Heesoo.
But it was his decision to ask her to run away when they barely counted as grown-ups. He had Heesoos best interest in mind and he dearly loved her, we saw that. But young love is not a superpower with which you can magically withstand anything life throws at you. And he and Heesoo had to lesen that the hard way.
What he seems to be forgetting is that he brought this cycle of poverty, struggling, loans upon himself by asking her to run away.
I think at some point he began freeloading on Heesoo and treating her poorly because he felt entitled to, because he gave up his promising future for her. And I think Heesoo thought so too, that he was allowed to do that because of how much he gave up for her. Their innocent young love turned toxic.
It's actually quite a realistic depicition of how love can change and twist over time when facing struggle after struggle. There is just so much one can take. It's honestly scary how fickle thr heart is.
Thanks for coming to my TED Talk.
Exactly it was perfect
I mean the way you explained it , was perfect
I just want to know what triggered him to change and treat her poorly